// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/disk_cache/simple/simple_util.h"

#include <windows.h>

#include "base/files/file_util.h"
#include "base/format_macros.h"
#include "base/rand_util.h"
#include "base/strings/stringprintf.h"
#include "net/disk_cache/cache_util.h"

namespace disk_cache {
namespace simple_util {

    bool SimpleCacheDeleteFile(const base::FilePath& path)
    {
        // Even if a file was opened with FLAG_SHARE_DELETE, it is not possible to
        // create a new file with the same name until the original file is actually
        // deleted. To allow new files to be created with the new name right away,
        // the file is renamed before it is deleted.

        // Why a random name? Because if the name was derived from our original name,
        // then churn on a particular cache entry could cause flakey behaviour.

        // TODO(gavinp): Ensure these "todelete_" files are cleaned up on periodic
        // directory sweeps.
        const base::FilePath rename_target = path.DirName().AppendASCII(base::StringPrintf("todelete_%016" PRIx64,
            base::RandUint64()));

        bool rename_succeeded = !!MoveFile(path.value().c_str(),
            rename_target.value().c_str());
        if (rename_succeeded)
            return DeleteCacheFile(rename_target);

        // The rename did not succeed. The fallback behaviour is to delete the file in
        // place, which might cause some flake.
        return DeleteCacheFile(path);
    }

} // namespace simple_util
} // namespace disk_cache
